It is much more important to know what sort of a patient has a disease than what sort of a disease a patient has.

Sir William Osler

When Francis S. Collins, MD, PhD, director of the US National Institutes of Health, and Harold Varmus, MD, director of theUS National Cancer Institute, recently commented on President Barack Obama’s new Precision Medicine Initiative,1 they highlighted the improvements in human health that could result from real-time measurements of blood glucose, blood pressure, and heart rhythm; from defining each individual’s unique genotypes, gut microbes, and peripheral blood immune cells; and from detecting circulating tumor cells or tumor DNA. There can be no doubt that if genomics, proteomics, pharmacogenomics, metabolomics, and epigenomics can be used to identify treatments that are uniquely tailored to the individual, the possibilities are almost unimaginable. However, an important element has been left out of the discussion. Individuals are not only distinguished by their biological variability; they also differ greatly in terms of how disease affects their lives. People have different personalities, resilience, and resources that influence how they will adapt to illness, so that the same disease can alter one individual’s personal and family life completely and not affect that of another person much at all. Diseases do not just affect individuals; they affect their families and friends, and their communities. As is true of biological variability, these important attributes of people have an impact on an individual’s susceptibility to disease, how that disease will reveal itself phenotypically, and the way that disease—and the individual with the disease—will respond to treatment. The influence of the unique circumstances of the person—the “personome”—is just as powerful as the impact of that individual’s genome, proteome, pharmacogenome, metabolome, and epigenome.